package com.ruoyi.common.security.utils;


import javax.crypto.Cipher;
import java.nio.charset.StandardCharsets;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.SecureRandom;
import java.security.Signature;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;
import java.util.HashMap;
import java.util.Map;


/**
 * @program: ruoyi
 * @description:
 * @author: wys1890
 * @create: 2021-01-11 11:58
 **/
public class RSAUtils {
    
    /**
     * 密钥长度 于原文长度对应 以及越长速度越慢
     */
    private final static int KEY_SIZE = 1024;
    /**
     * 用于封装随机产生的公钥与私钥
     */
    private static Map<Integer, String> keyMap = new HashMap<>(8);
    
    
    private static KeyPair keyPair;
    
    /**
     * 随机生成密钥对
     */
    public static void genKeyPair() throws NoSuchAlgorithmException {
        // KeyPairGenerator类用于生成公钥和私钥对，基于RSA算法生成对象
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
        // 初始化密钥对生成器
        keyPairGen.initialize(KEY_SIZE, new SecureRandom());
        // 生成一个密钥对，保存在keyPair中
        keyPair = keyPairGen.generateKeyPair();
        // 得到私钥
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
        // 得到公钥
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
        String publicKeyString = Base64.getEncoder().encodeToString(publicKey.getEncoded());
        // 得到私钥字符串
        String privateKeyString = Base64.getEncoder().encodeToString(privateKey.getEncoded());
        // 将公钥和私钥保存到Map
        //0表示公钥
        keyMap.put(0, publicKeyString);
        //1表示私钥
        keyMap.put(1, privateKeyString);
    }
    
    /**
     * RSA公钥加密
     *
     * @param plainText 加密字符串
     * @param publicKey 公钥
     * @return 密文
     * @throws Exception 加密过程中的异常信息
     */
    public static String encrypt(String plainText, PublicKey publicKey) throws Exception {
        Cipher encryptCipher = Cipher.getInstance("RSA");
        encryptCipher.init(Cipher.ENCRYPT_MODE, publicKey);
        byte[] cipherText = encryptCipher.doFinal(plainText.getBytes(StandardCharsets.UTF_8));
        return Base64.getEncoder().encodeToString(cipherText);
    }
    
    /**
     * RSA公钥加密
     *
     * @param plainText 加密字符串
     * @param publicKey 公钥
     * @return 密文
     * @throws Exception 加密过程中的异常信息
     */
    public static String encrypt(String plainText, String publicKey) throws Exception {
        //base64编码的公钥
        byte[] decoded = Base64.getDecoder().decode(publicKey);
        RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
        //RSA加密
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, pubKey);
        String outStr = Base64.getEncoder().encodeToString(cipher.doFinal(plainText.getBytes(StandardCharsets.UTF_8)));
        return outStr;
    }
    
    /**
     * RSA私钥解密
     *
     * @param cipherText 加密字符串
     * @param privateKey 私钥
     * @return 明文
     * @throws Exception 解密过程中的异常信息
     */
    public static String decrypt(String cipherText, PrivateKey privateKey) throws Exception {
        byte[] bytes = Base64.getDecoder().decode(cipherText);
        
        Cipher decriptCipher = Cipher.getInstance("RSA");
        decriptCipher.init(Cipher.DECRYPT_MODE, privateKey);
        
        return new String(decriptCipher.doFinal(bytes), StandardCharsets.UTF_8);
    }
    
    /**
     * RSA私钥解密
     *
     * @param plainText  加密字符串
     * @param privateKey 私钥
     * @return 明文
     * @throws Exception 解密过程中的异常信息
     */
    public static String decrypt(String plainText, String privateKey) throws Exception {
        //64位解码加密后的字符串
        byte[] inputByte = Base64.getDecoder().decode(plainText);
        //base64编码的私钥
        byte[] decoded = Base64.getDecoder().decode(privateKey);
        RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
        //RSA解密
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, priKey);
        String outStr = new String(cipher.doFinal(inputByte));
        return outStr;
    }
    
    /**
     * 签名
     *
     * @param data       待签名数据
     * @param privateKey 私钥
     * @return 签名
     * @throws Exception 解密过程中的异常信息
     */
    public static String sign(String data, PrivateKey privateKey) throws Exception {
        Signature privateSignature = Signature.getInstance("SHA256withRSA");
        privateSignature.initSign(privateKey);
        privateSignature.update(data.getBytes(StandardCharsets.UTF_8));
        byte[] signature = privateSignature.sign();
        return Base64.getEncoder().encodeToString(signature);
    }
    
    /**
     * @param data      : 待验签数据
     * @param signature : 签名
     * @param publicKey : 公钥
     * @return 验签结果
     */
    public static boolean verify(String data, String signature, PublicKey publicKey) throws Exception {
        Signature publicSignature = Signature.getInstance("SHA256withRSA");
        publicSignature.initVerify(publicKey);
        publicSignature.update(data.getBytes(StandardCharsets.UTF_8));
        byte[] signatureBytes = Base64.getDecoder().decode(signature);
        return publicSignature.verify(signatureBytes);
    }
    
    public static void main(String[] args) throws Exception {
        System.out.println(System.getProperty("file.encoding"));
        //生成公钥和私钥
        genKeyPair();
        
        String message = "RSA测试ABCD~!@#$";
        System.out.println("原文:" + message);
        String messageEn = encrypt(message, keyPair.getPublic());
        System.out.println("密文:" + messageEn);
        String messageDe = decrypt(messageEn, keyPair.getPrivate());
        System.out.println("解密:" + messageDe);
        // 签名
        String sign = sign(message, keyPair.getPrivate());
        System.out.println("签名:" + sign);
        boolean verify = verify(message, sign, keyPair.getPublic());
        System.out.println(verify);
        
    }
}
